Decoding Strategies
Christian B. Schlegel, Lance C. Pérez · 2004
There are a great variety of decoding algorithms for trellis codes. Until very recently, the main objective of a decoding algorithm was the successful identification of the transmitted symbol sequence, accomplished by so-called sequence decoders. These sequence decoders fall into two main groups: the tree decoders and the trellis decoders. Tree decoders explore the code tree, as defined in this chapter, and their most well-known representatives are the sequential algorithms and limited-size breadth first algorithms, such as the M-algorithm. Trellis decoders make use of the more structured trellis of a code, and its main algorithm is the maximum-likelihood Viterbi algorithm. Symbol probability decoding algorithms have recently become prominent and are discussed further in this chapter. In the appendix 7.A we calculate the vector Euclidean distance for a specific set Cp of retained paths.